PURPOSE: To regenerate a molding die by using a mixture of CeO2 and water to remove matters adhered to the molding surface of the molding die for an optical element.
CONSTITUTION: A molding die made of a superalloy or the like which is repeatedly used to form optical elements and has deposition such as metal component or the like on the molding surface is dipped in hydrofluoric acid and/or nitric acid of specified concn., and then subjected to overflow rinse with pure water. Then, the molding surface of the die is polished with an elastic material such as cotton, suede, paper, polyurethane, etc., impregnated with a mixture of CeO2 and water, preferably pure water. Or, the die is subjected to ultrasonic treatment in a mixture of CeO2 and water. Or, a mixture of CeO2 and water is injected through a nozzle to the molding surface of the die. Then, the die is subjected to ultrasonic cleaning in pure water and then to heat treatment at specified temp. in vacuum. Thus, the die is effectively regenerated.
UENO HIROSHI
MINATO AKITO
SUGAWARA TOMOAKI
OKUBO KATSUYUKI
